The biostatistical core will offer the flexibility of centralized data processing and statistical analysis for the proposed program subprojects as well as support pilot research endeavors (e.g. Pediatric pilot study). The objectives of the Biostatistical Core are: - To assist in the design of the studies, including sample selection, sample size determinations and binding of data collection. - To determine the hypotheses and the statistical procedures to be used for testing the hypotheses. - To develop and or modify questionnaires, data collection forms and databases. - To prepare data files and codebooks for data analysis. - To provide periodic and appropriate testing to maintain intra-rater reliability and retrain examiners if predetermined minimum criteria are not met. - To provide data analysis results to administration for communications such as publications, newsletters, seminars and meetings. - To respond quickly to requests for data.